3-D Flow Measurement of Oscillatory Thermocapillary Convection in Liquid Bridge in MEIS

Marangoni Experiment in Space (MEIS) has been conducted in the International Space Station (ISS) in order to clarify the transition processes of thermocapillary convection in liquid bridges. The use of microgravity allows us to generate long liquid bridges, 30mm in diameter and up to 60mm in length. Several flow visualization techniques have been applied to those large liquid bridges. 3-D PTV is used to reveal highly three-dimensional flow patterns that appear after the transition. Three CCD cameras are used to observe the motions of the tracer particles from different view angles through the transparent heated disk made of sapphire. Particle images are recorded in the HDD recording system in ISS and they are downloaded to the ground for data analysis. A conventional 3-D PTV technique and a newly-developed multi frame particle tracking method are combined to obtain the results that can help better understanding of oscillatory 3-D flow fields in the liquid bridges. It is shown that the flow pattern changes from a 2-D axisymmetric steady flow to an oscillatory 3-D non-axisymmetric flow under the supercritical conditions.